In an example of the above-noted article storage equipment, the transfer means is configured to perform a fetching process, with an article supporting member movable between a retracted position in the article transporting space and a projecting position to extend into each of the storage units and also vertically movable, for taking out the article storage container placed on the storage unit and a storing process for storing the article storage container placed on the article supporting member in the storage unit, and each of the storage units is formed of a plate-like member for receiving the container made of metal and having an opening through which the article supporting member in the projecting position vertically passes. The control means is configured to control the operation of the conveying means in performing the fetching process to extend the article supporting member to the projecting position at a fetching level lower than the plate-like member by a fixed amount, raise the article supporting member to a target fetching level higher than the fetching level by a raised amount for fetching, and then withdraw the article supporting member into the retracted position.
The above-noted article storage equipment is designed to allow the transfer means provided in the conveying means to move within the article transporting space defined in the front side of the storage section along the direction of arranging the storage units to the target storage unit and to allow the article supporting member forming the transfer means to perform the fetching process for taking out the article storage container stored in the target storage unit or the storing process for storing the article storage container in the storage unit. As the article storage container, various types of containers for storing the article including a bucket or an FOUP (Front Opening Unified Pod) for storing a substrate may be used.
The article storage container fetched in the fetching process is generally transported to an article access portion provided in the storage section, but sometimes transported to another storage unit. Similarly, the article storage container stored in the storage unit in the storing process is generally transported from the article access portion provided in the storage section, but sometimes fetched from another storage unit.
When the fetching process is performed with the article supporting member, the control means allows the article supporting member to extend to the projecting position to project into the storage unit at the fetching level lower than the plate-like member for receiving the container by the fixed amount. Next, the control means raises the article supporting member to the target fetching level higher than the fetching level by the raised amount for fetching. Then, the control means controls the operation of the conveying means to withdraw the article support member into the retracted position. The fetching level is determined to be a level where the article supporting member extended to the projecting position does not come into contact with the plate-like member forming the storage unit. The target fetching level is determined to be a level where the article supporting member withdrawn into the retracted position does not come into contact with the plate-like member forming the storage unit.
In this type of article storage equipment, it is required to perform an article confirmation process (stocktaking process, in other words) for confirming the presence of the article storage container stored in the storage unit. To this end, the equipment may be provided with a tag having identification information of the article storage container in the article storage container to perform the article confirmation process by reading out the identification information of the tag.
A conventional example for performing such an article confirmation process is disclosed in Japanese Unexamined Patent Application Publication No. 5-105204 in which article storage equipment includes a stacker crane acting as conveying means. In this equipment, a barcode label acting as a tag having identification information is attached to an article storage container, while a barcode reader acting as a reader for reading out the identification information of the tag is provided in a lift deck having a fork acting as an article supporting member. When execution of the article confirmation process is instructed, control means for controlling operation of the conveying means takes out the article storage container stored in a target storage unit to the lift deck in the fetching process, allows the barcode reader to read out the barcode label attached to the article storage container, and then stores the article storage container in the storage unit in the storing process.
Another conventional example is disclosed in International Publication No. WO 2006/059675 in which article storage equipment includes a stacker crane acting as conveying means. In this equipment, an RFID (Radio Frequency Identification) tag acting as a tag having identification information is attached to an article storage container, while an RFID reader acting as a reader for reading out the identification information of the tag is provided in a lift deck. When execution of the article confirmation process is instructed, control means for controlling operation of the conveying means takes out the article storage container stored in a target storage unit to the lift deck, allows the RFID reader to read out the RFID tag attached to the article storage container, and then stores the article storage container in the storage unit in the storing process.
It should be noted that the barcode label acting as the tag having the identification information is easily defaced. Further, it is required to precisely place the barcode label and the barcode reader in positions suitable for reading in order to have the barcode reader read out the barcode label. As a result, when the barcode label and the barcode reader are used, the article confirmation process may be performed less satisfactorily due to illegibility.
In contrast, when the RFID reader and the RFID tag are used, the RFID tag having the identification information does not become illegible due to defacement. Further, the RFID reader can read out the RFID tag even if the positional relationship between the RFID reader and the RFID tag is somewhat changed, as a result of which the article confirmation process may be performed satisfactorily.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 5-105204    Patent Document 2: International Publication No. WO 2006/059675